1. Field of the Invention
Apparatuses consistent with the present invention relate to a display device using external light and more particularly, to a display device using an auxiliary light source together with natural light or illumination light to improve visibility.
2. Description of the Related Art
Due to the development of communication and display technologies, portable communication terminals have recently been developed. Examples of such communication terminals are personal digital assistants (PDA), portable multimedia players (PMP), and digital multimedia broadcasting (DMB) terminals. Liquid crystal displays (LCDs) are a type of light receiving flat panel display, which do not emit light by themselves but form an image by selectively transmitting illumination light radiated from a light source onto each pixel. Thus a backlight unit is installed behind a liquid crystal display device.
A backlight unit can be classified as a direct light type or an edge light type according to the arrangement of light sources. Direct light type backlight units include a plurality of lamps which are installed directly under a liquid crystal display and which emit light directly onto a liquid crystal panel. Direct light type backlight units may also include a light source that is efficiently installed on a broad surface and thus is appropriate for a large screen display device such as a 30-inch or greater LCD TV. Edge light type backlight units are appropriate for displays of portable terminals since their light sources are typically installed at a lateral side of a light guide panel.
Portable communication terminals are used in a wide variety of locations, and are often used outdoors in sunlight where the brightness of the screen may be relatively dark, thus decreasing the visibility of the display, and therefore reducing the portability of the portable communication terminals.